Porting Slurm SPANK plugins to prologue scripts

[SteVwonder]

Here's a list of SPANK plugins that are in use on LLNL systems:

• drop-caches
• hugepages
• ip-isolate
• job-data (may be irrelevant with Flux's KVS)
• mpibind (already have other integration points)
• oom-detect
• overcommit-memory
• thp (transparent huge pages)
• userns

There are a few other ones in @grondo's repo (https://github.com/grondo/slurm-spank-plugins):

• addr-no-randomize
• setsched

We discussed these on a ☕ call. Just wanted to document these potential use cases and maybe save someone else the effort of looking it up later on down the road.